Longshore security officers plan to strike at the Port of Portland Nov. 25 if talks Friday don’t produce a contract. The move would freeze millions of dollars worth of freight including shipping containers, autos, steel, commodities and bulk cargo.

A strike by just 25 officers who work at the gates of three terminals would have an outsize effect because fellow members of the International Longshore and Warehouse Union would refuse to cross their picket lines.

A strike isn’t certain. The Port and security officers, who’ve been negotiating since June 30, 2011, might reach agreement today in a session with a mediator. Or further 11th-hour talks could produce a contract — an unlikely prospect, however, given an unfair-labor-practice complaint the Port filed Thursday accusing Local 28 of bargaining in bad faith.

But one thing is for sure under the ILWU’s West Coast collective bargaining agreement, said Jennifer Sargent, a union spokeswoman. The union’s longshore division, which includes terminal workers, is entitled to respect picket lines — including those established by the union’s warehouse division, which covers the security officers.

“Everyone is hopeful that a settlement can be reached,” said Craig Merrilees, a spokesman for the union’s warehouse division, in an email Thursday.